PSV Sizing For Two Phase Flow

(1)

PRV set pressure psig 60

Accumulation % 10

Pressure at PRV inlet Po psia 80.7

Temperature at PRV inlet T R

Liquid heat capacity btu/lb.R

Specific volume of two-phase system 0.3116

Specific volume of vapor Vapor mass fraction

latent heat of vaporization btu/lb

Ratio of specific heats of vapor k for D.2, D.4

vapor & liquid specific vol. difference for D.1, D.2

Sp. Vol evaluated at 90% of Po V9 0.3629 for D.3

Omega Parameter ω #DIV/0! D.1

#DIV/0! D.2 1.482 D.3 #DIV/0! D.4

Selected Value of Omega ω 1.482

Crictical Pressure Ratio 0.66 from graph D.1

Downstream Back pressure Pa psia 29.7

Crictical Pressure Pc 53.262

Flow is Critical Flow

back pressure ratio 0.36803

Mass Flux G 594.07

Mass Flow Rate W lb/hr 477430

Discharge Coefficient Kd 0.85

Back Presure Correction Factor Kb 1 from graph D.2

Correction Factor For Rupture disk Kc 1

Calculated Area of the Orifice A 37.82

Selected Orifice Designation 0 #N/A

PSV Sizing

(two phase flow)

Cp V_o _ft3_/lb Vvo ft3_/lb xo h_vlo V_vlo ft3_/lb ɳ_c ɳ_a lb/s.ft2 in2 in2

(2)

INPUT OUTPUT for D.2, D.4 for D.1, D.2 Boiling Range < 150 F Boiling Range < 150 F Boiling Range > 150 F For Nonflashing systems

from graph D.1 Pc > Pa Critical Flow

Pc < Pa Sub-Critical Flow

from graph D.2

(3)

D 0.11 0.11 E 0.196 0.196 F 0.307 0.307 G 0.503 0.503 H 0.785 0.785 J 1.287 1.287 K 1.838 1.838 L 2.853 2.853 M 3.6 3.6 N 4.34 4.34 P 6.38 6.38 Q 11.05 11.05 R 16 16 T 26 26 API Orifice Designations

(4)

D E F G H J K L M N P Q R T

(5)

Accumulation % 10

Pressure at PRV inlet psia 300.7

Temperature at PRV inlet R 519.67

psia 107.6

Liquid heat capacity btu/lb.R 0.6365

Liquid density at PRV inlet 31.92

Density at 90% of Ps for D.9

btu/lb 152.3 vapor & liquid specific vol. difference 0.9684

Omega Parameter ωs 8.497 D.8

#DIV/0! D.9

Selected Value of Omega ωs 8.5

Transition saturation pressure ratio 0.944

High Subcooling Region

Saturation Pressure Ratio 0.358

Critical Pressure Ratio from graph D.3 (used for Low Sub cooling Region)

Downstream Back pressure Pa psia 24.7

Crictical Pressure Pc 0 used for Low Sub cooling Region

Flow is Critical Flow

back pressure ratio 0.082

Mass Flux G #DIV/0! D.10 for Low Subcooling Region

7560.47 D.11 for High Subcooling Region

Volumetric Flow Rate Q GPM 100

Back Presure Correction Factor Kb 1 use graph D.4

Calculated Area of the Orifice A 0.21

Selected Orifice Designation F 0.307

PSV Sizing

P_o T_o Saturation Pressure at T_o P_s Cp ρ_lo _lb/ft3 ρ₉ _lb/ft3 latent heat of vaporization at P_s h_vls

V_vls _ft3_/lb ɳ_st ɳ_s ɳ_c ɳ_a lb/s.ft2 in2 in2

(6)

INPUT OUTPUT

Boiling Range < 150 F Boiling Range >150 F

High Subcooling Region

from graph D.3 (used for Low Sub cooling Region)

used for Low Sub cooling Region

D.10 for Low Subcooling Region D.11 for High Subcooling Region

use graph D.4

(7)

D 0.11 E 0.196 0.11 F 0.307 0.196 G 0.503 0.307 H 0.785 0.503 J 1.287 0.785 K 1.838 1.287 L 2.853 1.838 M 3.6 2.853 N 4.34 3.6 P 6.38 4.34 Q 11.05 6.38 R 16 11.05 T 26 16 26 API Orifice Designations

(8)

(9)

Accumulation % 10

Pressure at PRV inlet psia 674.7

Temperature at PRV inlet R 909.67

Vapor mass fraction at PRV inlet 0.5596

Specific volume of vapor ft3/lb 0.2462

Specific volume of two phase system ft3/lb 0.1549 psia

Noncondensable gas partial pressure psia

Liquid heat capacity btu/lb.R

Liquid density at PRV inlet

0.1737 for D.15 Latent heat of vaporization at PRV inlet btu/lb

Vapor & liquid specific vol. difference

Ratio of specific heats k

Inlet void fraction 0.8894

If Conditions Satisfied

Omega Parameter ω #DIV/0! D.14

Nonflashing Critical Pressure Ratio from graph D.1

Flashing Critical Pressure Ratio from graph D.1

Critical Pressure Ratio Not Required

Downstream Back pressure Pa psia

Crictical Pressure Pc 0

Flow is Subcritical Flow

Back Pressure Ratio ₀

Non flashing partial pressure ratio Flashing partial pressure ratio

#DIV/0! #DIV/0!

Mass Flux G #DIV/0! for Critical Flow

Non flashing Mas flux Gg #DIV/0!

Flashing Mass flux Gv Err:502

Mass Flux G #DIV/0! for Subcritical Flow

Mass Flow Rate W lb/hr

Back Presure Correction Factor Kb 1 use graph D.2

PSV Sizing

P_o T_o x_o V_vgo V_o Saturation Pressure at T_o P_vo P_go Cp ρ_lo _lb/ft3 Specific volume at 90% of P_vo v₉ _lb/ft3 h_vlo V_vlo _ft3_/lb α_o ɳ_gc ɳ_vc ɳ_c ɳ_a ɳ_g ɳ_v lb/s.ft2 lb/s.ft2 lb/s.ft2 lb/s.ft2

(10)

Calculated Area of the Orifice A #DIV/0! for Critical Flow

Calculated Area of the Orifice #DIV/0! for Subcritical Flow

Selected Orifice Designation #DIV/0! #DIV/0! for Critical Flow

Selected Orifice Designation #DIV/0! for Subcritical Flow

in2 in2 in2 in2

(11)

INPUT OUTPUT

For systems that satisfy all the following conditions, use D.14 otherwise use D.15

If Conditions Satisfied If Conditions Not Satisfied 1.0923 D.15

from graph D.1 Not Required

0.62 from graph D.1 69.7

418.314 Critical Flow

0.103305

for Critical Flow 2665.816

for Subcritical Flow

153830 0.85

use graph D.2 1 use graph D.2

1

iterate ɳg & ɳv to get same values in G31 & G32

(12)

for Critical Flow 2.72 for Subcritical Flow

for Critical Flow

(13)

D 0.11

E 0.196 0.11

F 0.307 0.196

G 0.503 0.307

H 0.785 0.503

For systems that satisfy all the following conditions, use D.14 otherwise use D.15 J 1.287 0.785

K 1.838 1.287 L 2.853 1.838 M 3.6 2.853 N 4.34 3.6 P 6.38 4.34 Q 11.05 6.38 R 16 11.05 T 26 16 26 API Orifice Designations

(14)

(15)

(16)

(17)

D.1

(18)

(19)

(20)

(21)

(22)

(23)

(24)

(25)

(26)

(27)

(28)